Weird LaTeX representation of sin^2 x

**Describe the bug**
LaTeX representation of sin^2 x depends on the way how the squared sinus was got.

**To Reproduce**
```js
math.parse('(sin(x))^2').toTex()
"{\\left(\\sin\\left( x\\right)\\right)}^{2}"

math.parse('sin(x)*sin(x)').toTex()
"\\sin\\left( x\\right)\\cdot\\sin\\left( x\\right)"

math.simplify(math.parse('sin(x)*sin(x)')).toTex()
"{\\sin\\left( x\\right)}^{2}"

math.simplify(math.parse('(sin(x))^2')).toTex()
"{\\sin\\left( x\\right)}^{2}"
```